Date: Tue, 14 Jan 2003 20:17:56 -0500 (EST) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Peter Wemm <peter@wemm.org> Cc: John Baldwin <jhb@FreeBSD.org>, Wilko Bulte <wkb@freebie.xs4all.nl>, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org, Nate Lawson <njl@FreeBSD.org> Subject: Re: cvs commit: src/sys/dev/acpica acpi_cpu.c Message-ID: <15908.46788.141735.858350@grasshopper.cs.duke.edu> In-Reply-To: <20030114230057.81B422A89E@canning.wemm.org> References: <20030114173224.A74488@grasshopper.cs.duke.edu> <20030114230057.81B422A89E@canning.wemm.org>
next in thread | previous in thread | raw e-mail | index | archive | help
Peter Wemm writes: > Andrew Gallatin wrote: > > John Baldwin [jhb@FreeBSD.org] wrote: > > > aggressive policies in the future. You could change the speed on > > > your desktop by changing the performance speed to be 6 (75%) using > > > the sysctl for example: > > > > The scary thing is that for my destop setup, I can turn my speed down > > to 25% on my P4 and not really feel a difference in xterms, editors > > and soforth. (I CAN see a difference, I just don't mind it much). > > > > Any idea about how much power this actually saves on a desktop? > > FWIW, we see a (measured) difference of about 50W on 2.2GHz P4's simply by > turning machdep.cpu_idle_hlt on and off. I expect the clock throttling > would make similar differences. For 1U rack-mount systems (especially in > California) this is a Big Deal. Yes, it is. 2 years ago, just as I was leaving Duke and the Enrons of the world were raping California consumers, some people in my research group were looking at doing energy-aware server load balancing. Eg, you suspend a server to save power if load is low, and at peak times you bring additional servers on line. We were using PIIIs and APM, waking with wake-on-lan. I bet everything we did would translate to P4's and ACPI... See http://www.cs.duke.edu/ari/publications/balance-of-power.ps (That's more of a pie-in-the-sky thing.. I don't know where the paper with the hard numbers went). Drew To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?15908.46788.141735.858350>